data logs from test and tune 10-20-13

[TurboCajun]

ok purchased a new fuel pressure gauge to, taped it to the windshield, pressure was 42 line off 38 line on, i went for a ride I made about four hits, 22psi of boost and 62 psi on the fuel gauge all four times. got back home and put it in park my son noticed that the fuel pressure had dropped to 35 line on, I pulled the line off and it went to 42, I put it back on and it was 34-35. I had Brian go to the back of the car and move the wiring harness for the fuel pump and he said that the pump was kicking on and off (car is running in park). So I goto the back and this is the first time that I ever hear my fuel pump making the winning sound and it was kicking on and off. could it be going bad and just acting up once it has heated up?.


I also reset my TPS -- .42 idle 4.78 full throttle (no floor mat)


I checked voltage -- battery has 14 , alternator 14, scan master 13.7, when my fans kick on the battery and alt. goes to 13.8 and the scan master goes to 13.4.
what are the other important areas to check the see where I am losing between the alt and the ECM

[TurboCajun]

new walbro 340 is on it way.

[Steve Wood]

sometimes that is just the way the ecm outputs.  Remember that the ecm is converting an analog voltage to a digital output.  Sometimes you cannot find out why it is varying.

Check the voltage at the ecm-ign fuse and see what it says.  Then drop the column down a bit and wiggle the ignition switch around and see if the voltage changes on the scantool.    http://www.vortexbuicks-etc.com/ignition_switch.htm

I have seen major voltage changes due to bad connections at the switch

And I have seen corroded blades in the fuse block.

And then...I have measured the voltage going into the ecm and it would be several tenths higher than the scantool was showing so go figure.  I just figured the ecm was converting to digital and getting the wrong answer

[TurboCajun]

Thanks guys.

[TurboCajun]

ok received my new fuel pump and no where on it does it say 340, the numbers stamped on it is f20000169 - 02113-1 , how do I know if its a 255 or 340?

[Steve Wood]

that is the modern version of the 340.  The 340 is a 255 liter/hour pump

that is the number that was failing left and right a few years ago but was supposedly fixed by walbro.  I think the 340M was discontinued

[TurboCajun]

it states that it is good for up to 600hp , I should be ok with this on right

[Steve Wood]

yep

Grumpy went into the nines on one and spraying alky

[TurboCajun]

Thanks I just wanted to make sure before I dropped the tank,

[bescurred]

Thanks I just wanted to make sure before I dropped the tank,

When we slapped in a new pump in my dads GN we repainted the straps and tank...looks really clean since you can see the bottom of the tank from the rear...

[TurboCajun]

installed the new pump today but didnt get to test , what I pulled out of the tank was a GSS307M

[Steve Wood]

pretty old...but I replaced a 307 a few months ago, myself

[TurboCajun]

well , I put the fuel pressure gauge on the car and turned the key on and nothing.. both of the relays are working and shutting off after 3 sec, I am by myself and I am guessing it needs to be primed or I did something wrong in the tank, the 307m was already wired in with splices so I just used the connector from that and plugged into the new pump without checking the wires. (I was thinking that they are wired the same). I see on the wiring that there is a wire for pump priming, can someone tell me where it is, or do I have to jump the relay . remember I still have the 85 wiring

[Steve Wood]

if the pump is sitting in gasoline, it should need no priming.

on the ic cars, the pump test connector comes out of the wiring harness just below the alternator at the front end of the valve cover...also the tach connector.  Pump connector is a single gray wire.  Put 12 volts to it and the pump should run continually.

Did you hear the pump run for a couple of seconds when the key was turned on?

[TurboCajun]

no I did not hear the pump, I guess the tank will have to come back down.